A ratchet wrench is a type of wrench having at least one end that surrounds a nut or the head of a bolt. The wrench provides a mechanical advantage by applying torque to turn bolts, nuts or other items designed to interface with a wrench. The ratcheting mechanism allows the nut or bolt to be tightened or loosened with a reciprocating motion of the wrench, without requiring that the wrench be removed, refitted or repositioned after each turn.
A ratchet wrench includes ratchet and pawl components known in the mechanical arts to control and secure movement. Ratchets consist of a ratchet wheel, or gear wheel, and may include a spring assembly which applies pressure to a pivoting spring loaded finger called a pawl that engages the teeth. Either the teeth, or the pawl, are slanted at an angle, so that when the teeth are moving in one direction, the pawl slides up and over each tooth in turn, with the spring forcing it back in place with a “click” into the depression before the next tooth. When the teeth are moving in the other direction, the angle of the pawl causes it to catch against a tooth and stop further motion in that direction.
More specifically, a pawl is a movable component that operates as a lever. The pawl includes protuberances or other projections that engage the teeth of the ratchet wheel. The pawl is used to control the direction of the ratchet wheel rotation. In various embodiments, bolt engaging components may be used to apply pressure to a pawl (e.g., a spring loaded component) to keep a pawl engaged within the teeth of the ratchet wheel. A pawl may be machined, stamped or molded and constructed of one or more components having singular or multiple protuberances or projections.
Generally, a ratchet wheel is similar to other types of gear wheels. The pawl, which is usually spring-loaded to keep it engaged with the teeth of the ratchet wheel, will, when the ratchet wheel is rotated in one direction, slide up or “climb” the one side of a tooth. The pawl will then “jump” down into the bottom of the tooth space after going over the tip of the tooth, and the spring will have pushed it there. It will then ride up the slope of the next tooth as the ratchet wheel moves in the same “forward” direction. If the ratchet wheel is rotated in a “backward” direction, however, the pawl will only allow movement until it comes in contact with the opposite side of the next tooth back and it will jam there. This will limit backward movement of the ratchet wheel to a tooth length and no more, as long as the pawl is acting as intended to check the backward rotation.
One problem generally known in the art of box type wrenches using ratchet and pawl systems is that they are limited to a “nominal ratcheting arc,” which is defined by the number of teeth on the ratchet gear divided into 360 degrees. Various attempts are known in the art to create a reduced ratcheting arc ratchet wrench. However, these wrenches require a large rotational degree in order to use the wrench which is not possible in confined spaces. The need for such a large rotational movement lessens the utility of such wrenches. If a large degree of motion is required to rotate the ratchet, the wrench cannot be used in small or tight spaces. Attempts are also known in the art to create more efficient ratcheting mechanisms.
Accordingly, and in the view of these inventors, a need exists for a reduced ratcheting arc ratchet wrench assembly that can rotate a ratchet within small degrees. Further, it would be highly desirable to introduce a reduced ratcheting arc box end wrench and ratchet drive wrench using a ratchet and multiple pawl system that can operate at small rotational degrees and can be affordably manufactured and mass produced.